The present invention concerns a disposable sterile apparatus for the filtration of blood having a system for optimizing the recovery of blood in the passage from one container (pouch) to another.
The use of pre-assembled lines, designated tube sets, for single use to assure the sterility of the assembly for the filtration of blood contained in one pouch to a second empty pouch is now typical in the medical equipment sector. These sets are essentially composed of a tube in plastic equipped at the ends with quick couplings for a spike and a pouch that is empty of both liquid and air. At the center of the section of tube there is a filter designed to filter out any leukocytes contained in conserved blood and platelet concentrates, extraneous particles, etc. During use, the set is connected to a blood container, which is normally a pouch having the same dimensions and characteristics as the empty pouch, the container being suspended from a stand and, due to the effects of gravity, the medicament or the blood drips into the empty pouch. At the end of the process, i.e. when the upper container is empty, the final volume of liquid or blood present in the tube set tends to remain in the tube because of the negative pressure progressively created inside the assembly; because of this phenomenon a final quantity of blood or medical liquid is effectively lost during the filtration process.
Even if this negative pressure is relieved, because of the characteristic microporosity of the median filter element, and particularly, because after the filtration of blood the filter element tends to clog progressively thus reducing its degree of porosity in such a way that free air is no longer able to enter the filter medium, complete emptying of the pouch is prevented.
In practical terms, the so-called "bubble point" of the filter, this being the pressure value that the air must reach in order to pass through the capillaries of the filtration element soaked in blood, is not effectively reached. Therefore, the filter may not remain saturated.
To solve this problem, the Applicant has already developed a perfected filter, illustrated in FIG. 2, that comprises a filter body, having an inlet and an outlet, the filter being divided into at least two semi-chambers by an internal partition of filter material and one of these two chambers, the semi-chamber serving for evacuation being equipped with its own air inlet line in communication with the area external to the filter body.
Notwithstanding the above, if outside air is utilized to allow the filter to be completely evacuated, an inlet filter is required for purification purposes. Moreover, the air cleaned by the inlet filter will inevitably be less pure than the sterile air.
The purpose of the present invention is to eliminate the problems mentioned above by developing a disposable sterile apparatus for the filtration of blood with a system for optimization of the recovery of filtered blood, which serves to recover the blood remaining in the filter in an optimized manner with respect to known apparatuses and to do this in a completely sterile ambient.
Within the framework of the foregoing purpose, one object of the present invention is to create an apparatus of simple design and high reliability that can be manufactured relatively easily and at competitive costs.
A second and equally important object is to create an apparatus with the use of fewer elements than known devices.